A conventional vehicle rear drive assembly includes a drive shaft whose front portion is connected in slip joint relation to the interiorly splined rear portion of the transmission housing and whose angular position is characterized by an original angle with respect to the horizontal axis of a differential that is associated with the rear axle of the vehicle.
Pick-up trucks, vans, jeep-type vehicles as well as certain conventional automobiles are often made to travel over extremely rough terrain indigenous to rural or remote areas when being used by their drivers for such purposes as camping, sightseeing, joy-riding or exploring.
To enable the vehicle to safely operate at maximum effectiveness without damaging the drive assembly located along the underside thereof it is often necessary to elevate the rear section of the vehicle to increase its road clearance.
By so doing, the rear fender wells gain additional road clearance permitting the increased space therewithin to accommodate oversized tires which serve to provide greater road traction and overall more efficient vehicle handling.
In the past, rear lift blocks have been used to achieve the foregoing increase in elevation of the vehicle rear section by inserting them between the suspension means and axle housing.
The resulting displacement of the axle housing from the suspension caused a rearward slippage of the slip yoke assembly at the forward end of the drive shaft which inevitably resulted in an increase in the overall length of the drive shaft, increase in the original drive shaft angle by a substantial degree, and the misalignment of the rear universal joint coupling the drive shaft to the differential.
It has been shown that the effect of such displacement by a conventional rear lift block is detrimental to the maintenance of a capable and safe vehicle drive assembly operation insofar as the misalignment of that portion of the drive assembly which includes the drive shaft-rear universal joint connection, and the slip yoke joint connection, will cause excessive wear at the sites of these respective connections and will almost surely result in their premature failure. Less significant from a safety standpoint, but yet almost equally as annoying as a mechanical failure is the loud noises emanating from a poorly aligned drive shaft-rear universal joint connection.
The present invention has been devised to resolve these problems by utilizing rear lift blocks in conjunction with the drive assembly which, when properly installed between the rear vehicle suspension and the rear axle housing, will not only increase the rear vehicle elevation, allowing for greater road clearance and the accommodation of oversized tires, but will substantially restore the original drive shaft angle and the original drive shaft-rear universal joint operating alignment for maintaining the optimum effectiveness of the entire drive assembly operation.
It is, therefore, a major object of the present invention to provide in connection with a drive assembly of a driven vehicle, a means for differentially displacing the axle housing from the suspension means and substantially restoring the original drive shaft angle and the drive shaft-rear universal joint operating alignment while elevating the rear body of the vehicle for maintaining increased rear vehicle raod clearance and optimum effectiveness of the drive assembly operation.
It is a further object of the present invention to provide a displacement means which is substantially block-shaped and interposed between the suspension means and the axle housing, the top and bottom surfaces of the displacement means being oppositely congruent to the bottom surface of the suspension means and the upper surface of the housing, respectively.
It is still a further object of the present invention to provide at least two displacement means, each of the displacement means being substantially blocked-shaped and having a concavely formed lower surface defining a shim-like extension integrally formed with one end thereof and an anchor pin intergrally formed with the lower surface and received by a bore defined by the upper surface of the housing, the shim-like extension and the anchor pin cooperatively directing the drive assembly consecutively downward and forward with an upward rotation relative to vehicle rear axle for substantial restoration of the original drive shaft angle and the original drive shaft-rear universal joint operating alignment.